This invention relates generally to pressure control systems and more particularly concerns pressure regulators for tires.
Early tire pressure regulators facilitated automatic release of air from a tire if the tire pressure exceeds a predetermined maximum pressure of the tire. However, during the course of a race, as speeds and conditions change, tire pressures might fall below minimum desired tire pressures.
More recently, tire pressure regulators have been proposed which might facilitate automatic injection of air into a tire if the tire pressure falls below a predetermined minimum pressure. However, the proposed pressure regulators would accomplish air injection by use of compressed air cylinders. It is unlikely that the sanctioning bodies of any auto racing commissions will permit the presence of compressed air or gas cylinders anywhere on or in a race car. Furthermore, the counterbalancing of air tire pressure against the compressed air cylinder pressure results in inconsistencies in the speeds of injection and, as pressure equalization is approached when counterbalancing is complete, determination of all air injection to the tire will cease.
It is, therefore, an object of this invention to provide a tire pressure regulator which facilitates automatic release and injection of air out of and into a tire. Another object of this invention is to provide a tire pressure regulator which does not use compressed air cylinders as a pressure source. It is also an object of this invention to provide a tire pressure regulator which rapidly releases and injects air from and into a tire. A further object of this invention is to provide a tire pressure regulator capable of increasing tire pressure at a predictable and constant rate. And it is an object of this invention to provide a tire pressure regulator with the capacity to inject air into the tire throughout the duration of the race.
During the course of an auto race, tire pressure is constantly fluctuating, sometimes to extremes. Track speeds vary greatly between warm-ups and racing, between straightaways and curves, and between warning flags. Changes in tire revolutions-per-minute, in climatic and internal tire temperatures and in tire distortion associated with turns, acceleration and braking all contribute to changes in tire pressure.
The problems of coping with these tire pressure related issues throughout the changing conditions in the course of a race are further complicated because, at any given moment during the course of a race, each tire may be experiencing different forces depending on its location on the car. Outside tires are distorted by greater centrifugal forces than inside tires. Front tires run parallel on variable axes relative to the direction of the car while rear tires always run aligned on constant parallel axes. And any one tire might, at any time in a race, unexpectedly strike a feature on the track or an object not part of the track, causing a momentarily high spike in tire pressure.
Tires wear differently at different pressures and, in distance races, the time at which tire maintenance is required will be determined by the first of the tires in need. While wear is generally not an issue in sprint racing, sprint cars have continuous rear axles with no differential and the left rear tire has a smaller diameter than the right rear tire so that, in straightaways, one or both tires are skidding, a major cause of rapid heating.
At any distance, changes in tire pressure can change the response of the tire to the track. If the tires on a competing race-car can be kept within acceptable pressure levels throughout a race, the performance of both car and driver can be improved. And, depending on the length of the race, pressure control alone might sufficiently impact tire performance as to eliminate a time-consuming pit stop.
It is, therefore, an object of this invention to provide a vehicle-tire pressure-level regulator and method of regulation suitable for race-car competition. It is also an object of this invention to provide a vehicle-tire pressure-level regulator and method of regulation that closely tracks real-time tire pressure changes. It is a further object of this invention to provide a vehicle-tire pressure-level regulator and method of regulation that permits user selection of low and high threshold tire pressures. It is another object of this invention to provide a vehicle-tire pressure-level regulator and method of regulation that facilitates rapid correction to changes in tire pressure. It is yet another object of this invention to provide a vehicle-tire pressure-level regulator and method of regulation that takes into account transient spikes in tire pressure. It is also an object of this invention to provide a vehicle-tire pressure-level regulator and method of regulation that takes into account changes in tire pressure caused by tire distortion during vehicle turns. It is still another object of this invention to provide a vehicle-tire pressure-level regulator and method of regulation that is practical for independent use of a different regulator on each tire of the vehicle. A further object of this invention is to provide a vehicle-tire pressure-level regulator and method of regulation that minimizes depletion of available battery power for regulator operation. A corollary object of the invention is to provide a vehicle-tire pressure-level regulator and method of regulation having sufficient battery power to operate throughout a race. And it is an object of this invention to provide a vehicle-tire pressure-level regulator and method of regulation permitting rapid replacement of the regulator.